After years of laboring in virtual anonymity as Mr. Amy Grant, Texan Gary Chapman has his own talk show on The Nashville Network and is known by a vastly more flattering moniker: the David Letterman of country.

“I play a lot of boys,” reports Susan Graham, a svelte but buxom mezzo-soprano. Schooled for opera’s mischievous “trouser” roles by climbing trees and toilet-papering houses while she grew up in Midland, the 36-year-old earned a master’s degree in music at Texas Tech University in Lubbock and went on to win the Metropolitan Opera’s National …